Drought raises fears S.J. River could run dry

A water district official in south San Joaquin County is sounding the alarm that the county's namesake river could run dry this summer all the way to the edge of the Delta.

Alex Breitler

A water district official in south San Joaquin County is sounding the alarm that the county's namesake river could run dry this summer all the way to the edge of the Delta.

Not everyone believes such a dire prediction, but the fact that it is being discussed shows the seriousness of the drought.

The San Joaquin River is famous for being dry farther upstream, south of the Merced River. Most of its flow there has historically been diverted to farmers.

But the San Joaquin channel is typically wet once it passes the Merced and collects flows from the Tuolumne and Stanislaus rivers.

Even in the drought of 1976-77, the San Joaquin was flowing at Vernalis, just downstream of the Stanislaus.

Jeff Shields, general manager of the Manteca-based South San Joaquin Irrigation District, said he believes that could change this year.

"I don't know if it's ever happened or not, but in the circles that I spend time in, the conversation is revolving around what month the river will go dry," Shields said. "At Vernalis, there won't be water."

Shields' prognostication comes after his district and Oakdale Irrigation District sent a letter to federal officials saying they were "perplexed" by the recent decision to provide the Stockton area with more than half of its annual allotment of water from the Stanislaus River, despite historically dry conditions.

That water could otherwise have been stored in New Melones Lake for next year, or sent down the Stanislaus into the San Joaquin for farmers, fish or to freshen up the Delta.

A spokesman for the U.S. Bureau of Reclamation said the agency is looking at "new data related to the allocation" and will have new information later this month.

As for the San Joaquin running dry, "We don't see that being the case," said bureau spokesman Louis Moore. But, he added, it's unclear what might happen if there's no more rain and snow.

Rhonda Reed, a branch chief with the National Marine Fisheries Service, said she had not seen any analysis suggesting the river would run dry at Vernalis. She added in an email Friday that there are "many moving parts still in play" as officials attempt to put limited water to the best possible use.

In some ways, the San Joaquin basin is in worse shape than the larger and wetter Sacramento River basin, to the north.

The northern mountains wrung enough water out of February's storms to surpass the driest years on record for that region.

The San Joaquin didn't fare as well. With just 13 inches of precipitation, the basin remains almost 2 inches behind the total for 1923-24 and 2.5 inches behind 1976-77.

What that means is that relatively little runoff has splashed into the reservoirs that feed the San Joaquin. Much of the rain instead seems to have simply soaked back into the ground, Shields said.

Based on numbers he's seen, Shields said he believes New Melones Lake east of Stockton will hold less than 500,000 acre-feet of water this summer - about 20 percent full, perhaps worse.

Such low reservoir levels would make it difficult for dam operators to release any water downstream during the summer, Shields said.

John Herrick, a Stockton attorney who represents south Delta farmers, said a dry lower San Joaquin River is, indeed, possible.

What little water is released from reservoirs will be taken by upstream diverters closer to the dams, he said. Water users farther downstream could face a "crisis."

"Even with some low flow, it may not be enough to allow diversions," Herrick said.

Below Vernalis, farmers in the tidal Delta should still be able to pump water, although the quality of that water may be poor.

As for fish, officials say the greatest concern is making sure there's enough water in the river during the winter and spring to allow young salmon and steelhead to migrate out toward the ocean. Low flows in the summer could, however, harm threatened green sturgeon if they are in the area, Reed said.

Monty Schmitt, a scientist with the Natural Resources Defense Council, doubts the river would literally go dry.

Often, much of the water you see in the San Joaquin isn't snowmelt but is actually irrigation water that drained off farmers' fields farther south.

Despite the drought, some irrigation will still occur in the Valley, which means at least some water will likely seep into the San Joaquin and dribble toward the Delta, Schmitt said.

"It's not great water, but it is wet," said Schmitt, who has been working for years on an ambitious restoration plan for the upper San Joaquin.

Then again, because so much groundwater has been pumped out of the Valley over the years, much of the water carried in rivers or streams may simply sink back down into the ground while heading downstream.

Rivers lose an "immense" amount of water in that way, said Jeff Mount, a geologist and senior fellow with the Public Policy Institute of California.

The consequence is that if water managers want rivers to run at a certain level, they have to release even more water from reservoirs to do so.

With that in mind, there is "certainly potential" for the San Joaquin to run dry as far north as Vernalis, Mount said Friday.

Local farmer Jim McLeod said he's never heard of such a thing, and he's been working that area for more than half a century.

"I'm not so sure that's really going to happen," he said. "That, I'd have to see. But it does seem like everything is changing day by day."

Contact reporter Alex Breitler at (209) 546-8295 or abreitler@recordnet.com. Follow him at recordnet.com/breitlerblog and on Twitter @alexbreitler.

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